First pass of the Ansible EC2 inventory script

examples/scripts/ec2_external_inventory.py

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+#!/usr/bin/python -tt
+
+"""
+EC2 external inventory script
+=================================
+
+NOTE: This script assumes Ansible is being executed where the environment
+variables needed for Boto have been set:
+    export AWS_ACCESS_KEY_ID=''
+    export AWS_SECRET_ACCESS_KEY=''
+For more details, see: http://docs.pythonboto.org/en/latest/boto_config_tut.html
+"""
+
+import os
+import argparse
+import re
+from time import time
+from boto import ec2
+
+try:
+    import json
+except ImportError:
+    import simplejson as json
+
+
+### Settings
+
+# I can see other uses where this variable is something else, say if someone
+# is running Ansible within EC2, these might be internal IP addresses
+destinationVariable = "public_dns_name"
+vpcDestinationVariable = "ip_address"
+
+cachePath = "/tmp/ansible-ec2.cache"
+cacheMaxAge = 300  # seconds
+
+
+# Command line argument processing
+parser = argparse.ArgumentParser(description='Produce an Ansible Inventory file based on EC2')
+parser.add_argument('--list', action='store_true', default=True, 
+                   help='list instances (default: True)')
+parser.add_argument('--refresh-cache', action='store_true', default=False, 
+                   help='refreshes the cache by making API requests to EC2 (default: False, use cache)')
+args = parser.parse_args()
+
+
+
+# Instance IDs, tags, security groups, regions, availability zones
+inventory = {}
+
+
+def doApiCall(regionInfo):
+    # Loop over all regions
+    region = regionInfo.name
+    conn = ec2.connect_to_region(region)
+    
+    inventory[region] = []
+    
+    reservations = conn.get_all_instances()
+    for reservation in reservations:
+        for instance in reservation.instances:
+            if instance.state == 'terminated':
+                continue
+            
+            # Select the best destination address
+            if instance.subnet_id:
+                dest = getattr(instance, vpcDestinationVariable)
+            else:
+                dest =  getattr(instance, destinationVariable)
+    
+            if dest == None:
+                # Skip instances we cannot address (e.g. VPC private subnet)
+                continue
+    
+            # Group by instance ID (always a group of 1)
+            inventory[instance.id] = [dest]
+            
+            # Group by region
+            inventory[region].append(dest);
+                            
+            # Group by availability zone
+            if instance.placement in inventory:
+                inventory[instance.placement].append(dest);
+            else:
+                inventory[instance.placement] = [dest]
+            
+            # Group by security group
+            for group in instance.groups:
+                key = toSafe("security-group_" + group.name)
+                if key in inventory:
+                    inventory[key].append(dest);
+                else:
+                    inventory[key] = [dest]
+                    
+            # Group by tag keys
+            for k, v in instance.tags.iteritems():
+                key = toSafe("tag_" + k + "=" + v)
+                if key in inventory:
+                    inventory[key].append(dest);
+                else:
+                    inventory[key] = [dest]     
+                   
+    return formatInventory(True)
+
+def getInventoryFromCache():
+    cache = open(cachePath, 'r')
+    jsonInventory = cache.read()
+    return jsonInventory
+
+def getInventoryFromApiUpdateCache():
+    for region in ec2.regions():
+        doApiCall(region)
+    
+    jsonInventory = formatInventory(True)
+    cache = open(cachePath, 'w')
+    cache.write(jsonInventory)
+    cache.close()
+    return jsonInventory
+
+def toSafe(word):
+    return re.sub("[^A-Za-z0-9\-]", "_", word)
+    
+def formatInventory(pretty=False):
+    if pretty:
+        return json.dumps(inventory, sort_keys=True, indent=2)
+    else:
+        return json.dumps(inventory)
+    
+    
+# Do work here
+if args.refresh_cache:
+    jsonInventory = getInventoryFromApiUpdateCache()
+    
+elif os.path.isfile(cachePath):
+    modTime = os.path.getmtime(cachePath)
+    currentTime = time()
+    if (modTime + cacheMaxAge) > currentTime:
+        # Use cache
+        jsonInventory = getInventoryFromCache()
+    else:
+        jsonInventory = getInventoryFromApiUpdateCache()
+        
+else:
+    jsonInventory = getInventoryFromApiUpdateCache()
+    
+
+
+print jsonInventory
+